A technique that uses an inkjet print head to preform printing is known for printing identification information such as characters, letters, marks or the like on a tablet. In a tablet printing apparatus using this technique, tablets are conveyed by a conveying device such as a conveyor. Ink (for example, edible ink) is ejected from a nozzle of the inkjet print head located above the conveying device toward each tablet passing under the print head to print identification information on the tablet. As a conveying device, a device that sucks and holds tablets on a conveyor belt has been developed. In the conveyor belt of the suction type conveying device, a plurality of suction holes are formed along the conveying direction of the tablets to suck and hold the tablets.
In the suction type conveying device, tablets supplied onto the suction holes of the conveyor belt are held on the conveyor belt by suction from the suction holes. However, there are cases where the suction hole is not completely closed by the tablet. A portion of the suction hole may not be closed depending on the size, shape, or the like of the tablet. Besides, the suction hole may not be closed at all due to random supply of the tablets. When the suction hole is not completely closed by the tablet, air is sucked from the suction hole, which causes turbulence. When turbulence occurs, the posture of the tablet held on the conveyor belt may change from a desired posture (for example, horizontal posture) due to the wind pressure. When the posture of the tablet changes from the desired posture, the ink ejected from the nozzle may land on a position other than a desired position on the tablet, resulting in reduced print quality.